You can supply your buyer with all of the info that you used to price the trailer; comps with photos might work, particularly if he knows and has a solid relationship with his banker.
There are other, non-conventional sources of cash out there too right now. With interest rates as low as they are, there are oodles of folks who would like to make 6-7% percent on the money that they have in a CD or money market account that is currently paying 1.5-2%, particularly if your buyer is creditworthy and you're talking less than $10k.
AIR 2053 Current: 2006 Bigfoot 25RQ
Airstreamer Emeritus: 1953 Flying Cloud, 1957 Overlander, 1961 Bambi, 1970 Safari Special, 1978 Argosy Minuet, 1985 325 Moho, 1994 Limited 34' Two-door, 1994 B190 "B-Van"